*BEWARE: CONSTRUCTION ZONE*
“Grit is the stubborn refusal to quit.” Anonymous
For those of you interested in the gory details, here’s a peek in the workshop and final recap of the ordeal that finally got us where we needed to go. Venture on only if you don’t mind some grit between your teeth, inhale some abrasive, and feel the motor oil splatter.
You’ll get a little taste of why I wanted to quit and just refund the money. Lord knows there wasn’t profit in this project. But I don’t like to quit. I’m pretty stubborn when I set my mind to something.
Are the end links perfect? Perfectly imperfect. That is, on some links you can still see some maker’s marks. But I think they add to the finish.
And as with titanium as you know from COURG, they’ll pick up their own patina over time as you rock it. In the end, I decided to leave my personal endlinks rougher than all yours to remind me of the grit and abrasive tenacity it took to see this small batch hand crafted project to completion.
Well, you know full well now that the 3D printer we used, who had promised to help us finish the links, failed and gave up. I chased down an expert polisher from Omega, and he was too scared to try.
I went back to the 3D printer and pushed him to try again. He did. He tried taking the endlinks to another company. Both failed.
I realized I would have to do it myself to figure out how to make it happen. After a some research, I learned that some gunsmiths had success using bullet shell polishing tumblers to finish titanium. So, I purchased a tumbler with much anticipation and poured in some abrasive.
Trial & Error & Error & Error & Victory
From what I read of gunsmiths’ experiences, some said their projects took days of tumbling. Keep in mind, these tumblers are just glorified vibrating bowls.
The thing was ridiculously loud and something came loose and it got even more obnoxious. I worried my neighbors would go out of their mind. I was going out of my mind.
Three days later: FAIL. It did absolutely nothing besides make noise.
Looking back, I don’t know what I was thinking pitting a vibrating bowl against titanium grade 5. Wonderwoman Grace would call it optimism bias.
I set up a DIY mini-grinding cabinet and set to work with my dremel and some flapper wheels. But, when grinding titanium grade 5, because the metal is so hard the grinding produces a lot of heat. So, you need some kind of coolant.
You can’t use water because although it cools somewhat, it wouldn’t lubricate the cutting surface enough to make a difference. And so, I had to use motor oil.
(Scout likes hanging out while I do messy things.)
I dipped the endlink into the motor oil and then applied the dremel flapper wheel. Amazingly, it worked and I was able to grind the nubbly 3D printer textures to a smoother surface.
(And yes, the little DIY cabinet is surprisingly effective because I added an extra sealant in the lid. So, no oil or abrasive dust escaped into the area where I work on watches!)
But still, that surface was not nearly the right match. I need to get matte and smooth.
Maybe the gunsmith vibrating bowl would work now? Nope. I needed a real sand blaster.
Easy-Peasy Sandblast
WRONG. One limiting factor is that I have no room in my workshop in the apartment (a small walk-in closet) for a compressor, so I bought a mini-blaster used for etching glass in the hopes that it could do the job. It was like I was spraying baby powder at the endlink.
With some experimentation, I found what worked fairly well was 220 grit sandpaper. But I couldn’t sand the endlinks like you might imagine, because then I would get a sort of brushed finish.
I found that pressing a fresh part of the sandpaper on the endlink, while rubbing the end of a metal rod against the back of the sandpaper yielded a sort of sandblasted matte finish.
I tried this on a few links and it took hours and my fingers were getting seriously cramped, and the finish was not uniform enough. There was no way I’d get through 30!
Next, I tried various makerspaces and I only found one with a solid industrial sandblasting setup. But they weren’t equipped to let me switch out the abrasive they had preloaded, so I just had to take a shot.
The grit turned out too coarse. I liked the look of it, but it just didn’t match the case and band.
Time & Space
In the end, it took us going to Toronto and a week off from the day job to get them done because there’s no way I could have set this up in our apartment in Manhattan.
Living in a small apartment with two little children (and a very patient wife), and neighbors, it just wasn’t possible to get a large air compressor and real blast cabinet.
(That’s the final setup that made it happen! We’re now the proud owners of a bench grinder, a blast cabinet, heavy duty air compressor, and 40 lbs of proprietary abrasive mix!)
My plan was to hit the links again with a finer grit. Thankfully, I found a company called Spectrum Abrasives in Toronto specializing in supplying abrasives of all kinds. They’re a family owned business started by the dad, and now run by his two sons.
START OVER
Spectrum explained that I couldn’t reblast a blasted surface. A coarse grit blasted surface, can’t be blasted to an optimal finish with finer grit.
They recommended we use a special grinding wheel first to polish the surface lightly, and then hit the links with a blend of glass and aluminum oxide grit to match the band and case finish as close as possible.
A grandson of the founder, on the way to college in the fall, created the special abrasive blend for us. There’s just something special about a family business.